Fabrication of cellulose acetate membrane for monitoring freshness of minimally processed pomegranate (Punica granatum) arils

Abstract

This study examined the freshness of minimally processed pomegranate arils (MPPAs) under refrigeration conditions (5 ± 1 °C) stored in a polypropylene (PP) container sealed with PP nanocomposite multi-layered film (PP-NMF). The freshness indicator was fabricated using cellulose acetate coated with a combination of colorimetric pH dyes, which included bromocresol green (BCG), bromothymol blue (BTB) and methyl red (MR) in a ratio of 6:9:15. The fabricated indicator labels were attached inside the package headspace and observed an increase in CO2 (0.1 ± 0.01 to 0.9 ± 0.03% v/v) and a decrease in O2 (19.6 ± 0.01 to 18.8 ± 0.03% v/v) during storage (0–18 days). Color change of indicator labels was mainly caused by headspace concentrations that changed from dark to colorless for fresh and spoiled pomegranate arils. The PP-NMF used in MPPAs has high barrier properties, extending its shelf life in the refrigerator to over 15 days. The pomegranate arils stored for different periods of time showed significant changes in their physicochemical parameters. Over storage days, aerobic mesophilic bacteria (AMB) and yeast and mold count (YMC) increased to 4.90 ± 0.20 and 4.50 ± 0.20 log CFU g−1. An indicator developed for monitoring pomegranate arils stored in the refrigerator can detect freshness efficiently.